Each ship can only attack once per round unless you have an effect that grants another attack, such as Dengar or Veteran Turret Gunner. With such effects, a ship can attack a 2nd time in a round, but only that 2nd time (there's a limit of 1 bonus attack per ship per round, to keep things from getting crazy).
The lancer's turret offers versatility. Its forward arc has 3 dice, and it can cover its side or back with its (slightly weaker) turret arc, helping it to keep a target in arc for both shots and pilot/title abilities. And with a Gunner it could attack a 2nd time if desired.